Water Conservation Techniques and Graywater Reuse at the Single Household Level

Water has become a scarce resource on this earth. The population of the world is increasing tremendously while the earth's water resources are limited. Many efforts have been put forth to innovate water conservation measures. This work summarizes some analyses performed to investigate the effect and feasibility of applying different water conservation techniques in a US household with an emphasis on the use of graywater in both toilet flushing and landscape irrigation. Some outdoor and indoor conservation techniques are included such as xeriscaping, low-flow toilets, and graywater reuse for toilet flushing and landscape irrigation. The analysis was performed on a house of 3 residents. Twelve conservation scenarios were run through a model developed using the STELLA software (Systems Thinking in an Experimental Learning Lab with Animation). The model outputs are the total amount of potable water used per year and the total amount of wastewater discharged per year. The model results were evaluated and compared based on a cost-benefit analysis. Considering both the annual household savings and the payback period, the scenario which included all water conservation measures as well as graywater usage was the optimum. The optimum scenario achieved annual water savings of 93,000 gallons, which is about 50% of the annual water consumption in the base scenario. The graywater usage was responsible for about 35% of those water savings. The results of this study suggests that water conservation measures can be economically feasible in water scarce areas and stand to save homeowners a significant amount of money in the long run.